By Matthew Olin, President & CEO, Sierra Instruments
Traditionally, steam flow has been measured with a differential pressure device. This is typically an orifice plate. However, such devices are inherently volumetric flow measurements. As we have discussed in previous blog posts, changes in pressure and temperature will change the mass flow rate of steam. Even a “small” change of 10% in steam pressure will result in a 10% error in non-compensated mass flow. This means that, in a typical differential pressure measurement installation, the volumetric flow rate measured by the device must be compensated by measuring temperature and pressure, and then these three measurements (ΔP, T and P) integrated with a flow computer to calculate mass flow.